EXTENSION

Parameters

extension_name

The name of the extension. The extension_name will have names of the form cl_khr_<name> for an extension approved by the OpenCL working group and will have
names of the form cl_<vendor_name>_<name> for vendor extensions. The token all means that the behavior applies to all extensions supported by the compiler. The table below shows the legal values for extension_name:

Report an error on the #pragma OPENCL EXTENSION if theextension_name is not supported, or if all is specified.

disable

Behave (including issuing errors and warnings) as if the extension extension_name is not part of the language definition.
If all is specified, then behavior must revert back to that of the non-extended core version of the language being compiled to.
Warn on the #pragma OPENCL EXTENSION if the extension extension_name is not supported.

Description

The #pragma OPENCL EXTENSION directive is a simple, low-level mechanism to set the behavior for each extension. It does not define policies such as which combinations are appropriate; those must be defined elsewhere. The order of directives matter in setting the behavior for each extension. Directives that occur later override those seen earlier. The all
variant sets the behavior for all extensions, overriding all previously issued extension directives, but only if the behavior is set to disable.

The initial state of the compiler is as if the directive #pragma OPENCL EXTENSION all : disable was issued, telling the compiler that all error and warning reporting must be done according to this specification, ignoring any extensions.

Every extension which affects the OpenCL language semantics, syntax or adds built-in functions to the language must create a preprocessor #define that matches the extension name string. This #define would be available in the language if and only if the extension is supported on a given implementation.

Example

An extension which adds the extension string "cl_khr_fp64" should also add a preprocessor
#define called cl_khr_fp64. A kernel can now use this preprocessor #define to do something like the following:

#ifdef cl_khr_fp64
// do something using the extension
#else
// do something else or #error!
#endif